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onsemi BZX79C3V9-T50A
- Part No.:
- BZX79C3V9-T50A
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- DO-204AH, DO-35, Axial
- Datasheet:
-
BZX79C3V9-T50A.pdf
- Description:
- DIODE ZENER 3.9V 500MW DO35
- Quantity:
- Payment:
- Shipping:
Inventory:9,745
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Product details
Overview
BZX79C3V9-T50A from ON Semiconductor is a 3.9 V, 5% tolerance, 500 mW glass-passivated Zener diode in DO-35 package, rated for -65°C to +200°C operation, with 90 Ω dynamic impedance at 5 mA and 10 μA leakage current at 1 V reverse bias - used for precision voltage reference and overvoltage protection in low-power analog circuits.
For engineers reviewing the BZX79C3V9-T50A datasheet, pinout, applications, or equivalent options, key selection criteria include zener voltage tolerance (±5%), thermal coefficient (-3.5 mV/°C), junction capacitance (175 pF at 0 V), power derating (4.0 mW/°C above 75°C), and DO-35 mechanical compatibility with legacy through-hole designs.
Technical Context
The BZX79C3V9-T50A operates as a silicon planar Zener diode optimized for stable voltage regulation in low-current, low-noise applications. Its -3.5 mV/°C temperature coefficient ensures predictable drift across industrial temperature ranges, while its 90 Ω dynamic impedance at IZ = 5 mA supports tight regulation under varying load conditions.
Designed for DC voltage reference and transient suppression, it features glass-passivated junctions for enhanced reliability and moisture resistance. The DO-35 axial package enables manual soldering and socket-based prototyping without thermal stress concerns typical of surface-mount alternatives.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 3.7 V to 4.1 V at IZ = 5 mA - defines regulated output range for reference design accuracy |
| Power Dissipation (PD) | 500 mW @ TL ≤ 75°C - sets maximum continuous power handling before thermal derating |
| Dynamic Impedance (ZZ) | 90 Ω max at IZ = 5 mA - determines regulation stiffness against load current variation |
| Leakage Current (IR) | 10 μA max at VR = 1 V - limits standby power loss in high-impedance bias networks |
| Junction Capacitance (CJ) | 175 pF at VR = 0 V, f = 1 MHz - impacts high-frequency noise filtering and AC coupling behavior |
| Temperature Coefficient (TC) | -3.5 mV/°C - quantifies voltage drift per degree Celsius for thermal stability analysis |
| Operating Temperature | -65°C to +200°C - supports deployment in automotive engine bays and industrial control enclosures |
Pinout & Package
DO-35 glass axial package with cathode indicated by color band; leads are tinned copper alloy, 0.46 mm diameter, 3/8″ lead length standard for thermal rating compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower potential node during normal forward bias; unused in Zener regulation mode |
| Cathode | Zener breakdown terminal | Connected to higher potential node; reverse-biased to maintain 3.9 V reference at load |
Key Features
| Feature | Design Value |
|---|---|
| 5% Zener voltage tolerance | Enables consistent reference accuracy across production batches without individual trimming |
| Glass-passivated junction | Provides hermetic sealing against humidity and contaminants for long-term parameter stability |
| Negative temperature coefficient | Allows predictable compensation when paired with positive-TC components in reference circuits |
| Low leakage current | Minimizes error in high-resistance divider networks used for microcontroller ADC references |
Applications
| Automotive Sensor Reference | Industrial Analog Front-End |
|---|---|
Use Scenario: Providing stable 3.9 V reference for pressure sensor signal conditioning in engine control units. IC Role / Device Role / Timing Role: Zener diode acting as shunt voltage reference for op-amp biasing and ADC reference scaling. Use Value: Maintains ±5% reference accuracy over -40°C to +125°C ambient, enabling repeatable sensor calibration. | Use Scenario: Regulating supply rail for isolated RS-485 transceiver bias in programmable logic controllers. IC Role / Device Role / Timing Role: Shunt regulator clamping local 3.9 V rail to protect transceiver input stages from overvoltage transients. Use Value: Absorbs up to 500 mW surge energy while holding voltage within 100 mV of nominal, preventing latch-up. |
| Consumer Audio Power Supply | Medical Diagnostic Instrumentation |
Use Scenario: Generating clean 3.9 V bias for headphone amplifier ICs in portable audio devices. IC Role / Device Role / Timing Role: Low-noise voltage reference stabilizing analog gain stages in battery-powered amplifiers. Use Value: 175 pF junction capacitance minimizes RF coupling into sensitive audio paths, preserving SNR. | Use Scenario: Establishing calibrated threshold voltage for ECG front-end comparator circuits. IC Role / Device Role / Timing Role: Precision shunt reference defining trip point for patient safety overvoltage detection. Use Value: -3.5 mV/°C TC allows predictable drift compensation in firmware, meeting IEC 60601-1 accuracy requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4730A | Same 3.9 V nominal, but ±5% tolerance and 100 Ω ZZ at 5 mA vs. 90 Ω for BZX79C3V9-T50A | Higher dynamic impedance may reduce regulation accuracy in low-current sensor bias networks | Prefer BZX79C3V9-T50A where tighter impedance control is required for precision references |
| MMSZ4685 | SOD-123 surface-mount package, same 3.9 V rating, but 500 mW derated to 350 mW at 25°C and 100 Ω ZZ | Not suitable for through-hole prototyping or high-temp through-hole assemblies requiring DO-35 thermal mass | Select BZX79C3V9-T50A for legacy board compatibility and higher thermal robustness in leaded designs |
Compared with 1N4730A and MMSZ4685, the BZX79C3V9-T50A delivers lower dynamic impedance and superior thermal performance in axial-leaded configurations, making it optimal for industrial and automotive applications demanding long-term stability and manual assembly support.
Availability
BZX79C3V9-T50A is available at Aetrix Electronics and suitable for automotive sensor reference, industrial analog front-end, and medical diagnostic instrumentation requiring stable component supply and long-lifecycle availability.
Supply support for BZX79C3V9-T50A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and medical markets.
The BZX79C3V9-T50A belongs to the BZX79C series of general-purpose Zener diodes designed for cost-sensitive, high-reliability voltage regulation and protection in through-hole applications across harsh environments.
FAQ
What is the Zener voltage tolerance for BZX79C3V9-T50A?
The BZX79C3V9-T50A has a ±5% Zener voltage tolerance, meaning its regulated voltage falls between 3.7 V and 4.1 V when tested at 5 mA reverse current and 25°C. This tolerance is specified in the ON Semiconductor datasheet Rev. 3 and applies to all units shipped under this part number. The BZX79C3V9-T50A maintains this tolerance across its full operating temperature range, supporting consistent performance in unregulated power supplies and reference circuits.
Does BZX79C3V9-T50A have a specified forward voltage?
Yes, the BZX79C3V9-T50A specifies a maximum forward voltage (VF) of 1.5 V at 100 mA forward current, per the "VF Forward Voltage" note in the official datasheet. This parameter is relevant for applications where the device may experience brief forward conduction during power-up sequencing or fault conditions. The BZX79C3V9-T50A's forward characteristic remains consistent with other BZX79C-series diodes, ensuring predictable behavior in bidirectional protection schemes.
What is the thermal derating behavior of BZX79C3V9-T50A above 75°C?
The BZX79C3V9-T50A derates linearly at 4.0 mW/°C above a lead temperature of 75°C, as defined in the Absolute Maximum Ratings table. This means its usable power dissipation drops from 500 mW at 75°C to 400 mW at 100°C. This derating applies specifically to the DO-35 package with 3/8″ lead length, and must be applied in thermal design calculations for BZX79C3V9-T50A in enclosed or high-ambient environments such as automotive ECUs or industrial motor drives.
Is BZX79C3V9-T50A suitable for high-frequency applications?
The BZX79C3V9-T50A exhibits 175 pF junction capacitance at 0 V reverse bias and 1 MHz, limiting its effectiveness above ~1 MHz in AC-coupled or RF bypass roles. While usable for low-speed voltage clamping and DC reference, the BZX79C3V9-T50A is not recommended for RF filtering or fast transient suppression where sub-100 pF capacitance is required. For such cases, consider TVS diodes or specialized RF Zeners instead of the BZX79C3V9-T50A.
How is cathode identification implemented on BZX79C3V9-T50A?
The cathode of the BZX79C3V9-T50A is marked by a distinct color band on the DO-35 glass body, per the "COLOR BAND DENOTES CATHODE" note in the datasheet. This band aligns with industry-standard axial diode marking conventions and is visible under standard visual inspection. No secondary marking (e.g., "K" or "C") is used - the BZX79C3V9-T50A relies solely on the band for polarity identification, ensuring unambiguous orientation during manual assembly and automated optical inspection.
BZX79C3V9-T50A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- DO-204AH, DO-35, Axial
- Packaging:
- Cut Tape (CT)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 3.9 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 90 Ohms
- Current - Reverse Leakage @ Vr:
- 10 µA @ 1 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 100 mA
- Operating Temperature:
- -65°C ~ 200°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-35
BZX79C3V9-T50A FAQ
1.How can I place an order for BZX79C3V9-T50A through Aetrix?
Please submit a Request for Quotation (RFQ) for BZX79C3V9-T50A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BZX79C3V9-T50A reliable?
The price and inventory of BZX79C3V9-T50A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BZX79C3V9-T50A is usually 5 days.
3.What payment methods are accepted for BZX79C3V9-T50A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BZX79C3V9-T50A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BZX79C3V9-T50A?
BZX79C3V9-T50A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BZX79C3V9-T50A order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BZX79C3V9-T50A?
For technical support, including BZX79C3V9-T50A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BZX79C3V9-T50A requirements.
6.How does Aetrix verify that BZX79C3V9-T50A is sourced from the original manufacturer or authorized distributors?
All BZX79C3V9-T50A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BZX79C3V9-T50A meets industry standards.
7.What is the process for return or replacement of BZX79C3V9-T50A?
All BZX79C3V9-T50A units undergo pre-shipment inspection (PSI). If there is an issue with BZX79C3V9-T50A, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BZX79C3V9-T50A part is unused and in its original packaging.
Return procedure for BZX79C3V9-T50A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BZX79C3V9-T50A Tags
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